I have an Exmark 28 hp lazer z with the kohler efi engine. I have a blower for it so I use it in the winter. The first winter I used it I had no problems. Even on a -10 F day it started right up. I use the synthetic 5W30 oil which helps. The 2nd winter it began acting up and now it is doing it again. When I start it up it runs for about 2 seconds and then stops. After that it starts really hard. I have to crank it for a long time and it sputters and coughs and I just keep cranking until it sounds like it might stay running. Eventually it starts. Once I get is started it runs fine. I've had the fuel system drained, new plugs, new battery. I've monitored the fuel pressure when it acts up and it looks normal at 30psi. Any ideas? Thanks.